Session: 15-01-01: ASME International Undergraduate Research and Design Exposition

Paper Number: 95954

95954 - Design and Analysis of Poly(ε-Caprolactone) Flow Diverters 

Flow diverters (FDs) are the fine-meshed tubes that are used as endovascular devices to regulate blood flow inside the aneurysm and induce intra-aneurysmal thrombus to dissolve aneurysms. Current FDA-approved FDs are based on metallic microwires and stay forever in the body. Studies show that metallic FDs can cause late thrombosis, stenosis, infarction, and persistent mild inflammation on the blood vessel walls. In addition, the permanent placement of metallic implants interferes with non-invasive electromagnetic diagnostics and procedures such as MRIs, CT scans, X-rays, etc. Hence the objective of this research is to develop flow diverters based on the bioresorbable materials that can be resorbed by the body after curing aneurysms. Here we present the design, mechanical testing, and analysis of bioresorbable poly-ε-caprolactone (PCL) flow diverters.

PCL FDs were designed and fabricated using an in-house hybrid fabrication unit based on spinning technology and fused deposition modeling technique. The process parameters of the fabrication unit, i.e., spinning speed, translational motion, and extruder temperature, were varied to produce PCL FDs with 60%, 70%, and 80% porosities. Various combinations of BaSO4 and PCL were mixed with Aceton to form a paste for radiopacity coating. The PCL FDs were coated with ultra-thin layers of BaSO4 and PCL paste as 2 mm wide rings at the two ends and middle of the FDs for visibility during the placement through an angiogram. The FD strut sizes, pore shape, pore densities, and quality of the FD surface were evaluated using a scanning electron microscope (SEM) and 3D profilometers. The visibility of the PCL FDs was assessed from X-ray images taken by a hand-held X-ray machine. The radial strength, bending flexibility, and longitudinal strength were evaluated using the UniVert testing machine, an universal testing machine for the biomaterials. The PCL FDs were loaded into 4 Fr catheters and deployed on an optically transparent aneurysm flow model.

The results showed that higher spinning rate and translational motion produced thinner strut and elongated diamond-shaped pores. The shape of the pore was mainly dependent on the translational motion, while the extruder temperature and spinning rate had more influences on the structure of the strut. The FD surfaces were smoother and uniform. Various combinations of BaSO4 and PCL paste coating were visible under the X-ray image. However, 2:1 BaSO4 and PCL coating were most vivid and convenient to coat. All combinations of PCL FDs were extremely flexible and were able to return to their original shape after complete bending and twisting. The radial crimping showed almost 95% recovery. The average maximum longitudinal strength was found to be 2.5 N before breaking. There was no significant distortion within the PCL FDs structure after deployment in the aneurysm flow model. This study will help in the development of a functional bioresorbable flow diverter.

Presenting Author: Seth Harriet University of Central Oklahoma

Presenting Author Biography: Seth Harriet is junior mechancial engineering major undergraduate student and research assistant.

Authors:

Mohammad Hossan Univ Of Central Oklahoma
Seth Harriet University of Central Oklahoma
Vishal Barot University of Central Oklahoma